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Spreading Wildfires in California Have Killed 4

At least 62,000 people have been evacuated amid a grueling heat wave, the coronavirus pandemic and air thick with smoke.

Published Aug. 20, 2020 Updated Aug. 21, 2020

This briefing has ended. The latest updates on the California wildfires are here ..
https://www.nytimes.com/2020/08/21/us/ca-fires.html .

Here’s what you need to know:

* Three people were killed by wildfires in Napa County, and one in Solano County.

* Evacuees seeking shelter must weigh risk of the coronavirus.

* Smoke is making the air unhealthy to breathe in many places.

* The University of California, Santa Cruz, is put under an evacuation order.

* The historic Big Basin Redwoods State Park has been badly damaged by fire.

* Poor planning by grid managers and regulators led to rolling blackouts.

* California’s ‘lightning siege’ has connections to climate change.

A state fire official described it as a “historic lightning siege” — the nearly 11,000 bolts of lightning that struck California over 72 hours this week and ignited 367 wildfires.

Such a flurry of strikes is unusual in California, where it normally takes a full year to tally up 85,000 or so lightning flashes, said Joseph Dwyer, a physicist and lightning researcher at the University of New Hampshire. That is far fewer than Florida, one of the most lightning-prone states, which averages about 1.2 million flashes a year.

Lightning occurs during storms with strong updrafts. During these storms, charged ice particles in clouds collide, generating an electric field. If the field is strong enough, electricity can arc to the ground as lightning, which can ignite dry vegetation: Nationwide, about 15 percent of wildfires start this way.

Strikes across the United States are expected to increase with climate change, as warmer air carries more water vapor, which provides the fuel for strong updraft conditions. A 2014 study estimated that strikes could increase by about 12 percent per 1.8 degree Fahrenheit (1 degree Celsius) of warming, or by about 50 percent by 2100.

A tweeted video

https://www.nytimes.com/2020/08/20/us/ca-fires.html